1. Field of the Invention
The present invention generally relates to masks (the term encompassing any of various types of masks and reticles) defining a pattern intended to be xe2x80x9ctransferredxe2x80x9d (i.e., projection-exposed) onto a substrate that is sensitive to radiation (e.g., light or X-rays) or a charged-particle beam (e.g., an electron beam or ion beam) using microlithographic exposure tools.
2. Description of the Related Art
Semiconductor integrated circuit (IC) technology has advanced miniaturization and increased integration of semiconductor elements in IC devices by continued improvements provided by optical lithography techniques and tools.
Optical stepper tools and other projection-exposure tools typically use light for transferring the pattern from the mask to the substrate for imprinting integrated circuit patterns on semiconductor wafers and other substrates. Such tools use a projection-optical system to effect transfer of the mask pattern to the substrate. xe2x80x9cTransfer toolsxe2x80x9d encompass any of the various projection-exposure systems operable to perform projection-imprinting (transfer) of a pattern defined by a mask onto a surface of a sensitive substrate. Transfer tools include steppers, scanners, and other lithographic exposure systems. Most transfer tools are xe2x80x9creducingxe2x80x9d meaning that the image of the pattern formed on the substrate is smaller than a corresponding pattern on the mask.
With continued miniaturization of circuit patterns with attendant resolution limitations of light, much recent research and development in microlithography has been directed to transfer tools that use shorter-wavelength electromagnetic radiation (e.g., X-rays) or charged-particle beams (xe2x80x9cCPBs,xe2x80x9d e.g., electron beams, ion beams) rather than visible or UV light.
In conventional microlithography exposure systems, information of the mask patterns must be supplied to the microlithography tool (xe2x80x9cthe stepperxe2x80x9d) during the exposure process. For example, using charged particle beam (CPB) systems that include electron beam projection lithography (EPL), pattern data such as pattern density and the within membrane placement of each sub-field membrane must be supplied to the microlithographic exposure tool. The pattern density is needed for focus adjustments and the center field location is needed to properly align the pattern. Known techniques include electronically providing this pattern data to the stepper over a network connection.
Patterning data typically is provided to the microlithographic tool (e.g., a stepper) by complex network control connections or by an operator manually via portable data storage media that is loaded into the stepper. Such pattern data transfer is subject to ambiguities associated with each mask (reticle) during processing and not reliable.
It is, therefore, an object of the present invention to provide a structure and method for associating pattern data with each mask without the need for added system support and attendant network connection(s) between the pattern data storage component(s) and the microlithographic tool.
The invention provides patterning data associated with each reticle, which physically resides directly on the reticle. This patterning data typically is provided to the microlithographic tool by complex network control connections or loaded manually from portable data storage media. The invention eliminates these intermediate network connections to the microlithographic tool, thereby improving IC productivity. Two preferred embodiments of the invention are provided wherein the pattern data is stored in the mask via a memory device built into the mask and physically encoding the pattern data on the surface of the mask.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.